Add initial pinctrl driver to support pin configuration for
LPASS (Low Power Audio SubSystem) LPI (Low Power Island) pinctrl
on SM8250.

This IP is an additional pin control block for Audio Pins on top the
existing SoC Top level pin-controller.
Hardware setup looks like:

TLMM GPIO[146 - 159] --> LPASS LPI GPIO [0 - 13]

This pin controller has some similarities compared to Top level
msm SoC Pin controller like 'each pin belongs to a single group'
and so on. However this one is intended to control only audio
pins in particular, which can not be configured/touched by the
Top level SoC pin controller except setting them as gpios.
Apart from this, slew rate is also available in this block for
certain pins which are connected to SLIMbus or SoundWire Bus.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20201202163443.26499-3-srinivas.kandagatla@linaro.org
[Add some dependencies]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>